Method and apparatus for identifying mobile network protocol capabilities

ABSTRACT

A method and apparatus for improving handover in an IEEE 802.21 compliant communication network. A query is transmitted from a wireless transmit/receive unit (WTRU) to a media independent handover (MIH) server (MIHS). The WTRU includes a target point of attachment (PoA) and/or a preferred mobile inter protocol (MIP) method. The WTRU receives a response from the MIHS indicating the MIP method supported by the target PoA. Based on the received response, the WTRU may make an informed decision regarding handover.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.12/062,792, filed Apr. 4, 2008, which claims the benefit of U.S.provisional application No. 60/910,494, filed Apr. 6, 2007, all of whichare incorporated by reference as if fully set forth.

TECHNOLOGY FIELD

This subject matter disclosed herein is generally related to wirelesscommunication systems.

BACKGROUND

The IEEE 802.21 standard defines mechanisms and procedures that aid inthe execution and management of inter-system handovers. IEEE 802.21defines three main services available to Mobility Managementapplications, such as Client Mobile Internet Protocol (Client MIP) orProxy MIP. Referring to FIG. 1, these services are the Event Service100, the Information Service 105 and the Command Service 110. Theseservices aid in the management of handover operations, system discoveryand system selection by providing information and triggers from lowerlayers 115 to upper layers 120 via a media independent handover (MIH)function 125.

Within the context of the command service 110, functionality is definedfor querying an MIH compatible node to determine the node's InternetProtocol (IP) capabilities. This is accomplished via theMIH_Network_Address_Information Request message sent from a wirelesstransmit/receive unit (WTRU) and the MIH_Network_Address_InformationResponse message sent from the MIH compatible node.

Certain systems, such as the Third Generation Partnership Project LongTerm Evolution (3GPP LTE) system, utilize a hybrid mobility schema whereboth client MIP and proxy MIP are used. Proxy MIP is preferred becauseof its well known advantages such as elimination of over-the-air (OTA)tunneling overhead, greater flexibility, and reduced latency. However,in a roaming scenario it is highly likely that a WTRU will encounternetworks that do not support proxy MIP. In this scenario, client MIP isused.

Under the current IEEE 802.21 standard, a WTRU is unable to determinewhether an accessible network provides support for localized mobilityprocedures (such as proxy MIP) or only conventional mobility procedures(such as client MIP). This information is an important criterion innetwork selection. Selection of a network with undesirable mobilitymanagement procedures will result in sub-optimal mobility scenarios.Furthermore, if a WTRU is able to determine the MIP characteristics of anetwork, the WTRU may trigger IEEE 802.21 procedures to improve mobilityhandling.

SUMMARY

A method and apparatus for improving handover in IEEE 802.21 compliantcommunications. A query is transmitted from a WTRU to a MIH server(MIHS). The WTRU includes a target point of attachment (PoA) and/or apreferred MIP method. The WTRU receives a response from the MIHSindicating the MIP method supported by the target PoA. Based on thereceived response, the WTRU may make an informed decision regardinghandover.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description, given by way of example and to be understood inconjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of MIH services;

FIG. 2 shows a wireless communication system in which a WTRU is unableto obtain mobility management information regarding diverse networkslocated therein;

FIG. 3 shows an enhanced network of FIG. 2, in which a WTRU may query aMIH server and receive mobility management information regarding diversenetworks located therein;

FIG. 4 is a diagram of a MIH_Network_Address_Information_Request messagedisclosed herein;

FIG. 5 is a diagram of a MIH_Network_Address_Information_Responsemessage disclosed herein; and

FIG. 6 is a block diagram of a WTRU and an access point configured totransmit and receive the messages of FIG. 4 and FIG. 5.

DETAILED DESCRIPTION

When referred to herein, the terminology “wireless transmit/receive unit(WTRU)” includes but is not limited to a user equipment (UE), a mobilenode, mobile station (STA), a fixed or mobile subscriber unit, a pager,a cellular telephone, a personal digital assistant (PDA), a computer, orany other type of user device capable of operating in a wirelessenvironment. When referred to hereafter, the terminology “access point”includes but is not limited to a Node-B, a site controller, a basestation (BS), or any other type of interfacing device capable ofoperating in a wireless environment.

A solution to the aforementioned problem is to provide a WTRU withinformation regarding the MIP capabilities of a network. The network ispreferably a prospective network to which the WTRU is considering ahandover to. In one embodiment, a request message includes an identifierof a network that is the target network for handover. An associatedresponse message includes MIP capabilities of the identified network.

FIG. 2 is a communication system 200 including two distinct networks 205and 210 where mobility management information is not available to WTRU215. network 205 includes multiple network routers (220, 225) and threeaccess points 230, 235, and 240. A server 245 of the first network 205communicates with the network routers 220, 225 and servers of othernetworks via the Internet 250, for example. The second network 210 alsoincludes a server 255, a network router 260, and an access point 265. Itis noted that the first network 205 and second network 210 may be of thesame or different type.

In the communication system 200, localized mobility managementprotocols, such as proxy MIP, are supported only in the first network205. When WTRU 215 is communicating with access points 230, 235, and 240(locations A, B, and C, respectively), localized mobility management isavailable for inter-access point handovers. However, second network 210does not support localized mobility management protocols and insteadsupports only client MIP. When WTRU 215 is in communication with thesecond network 210 (position D) via access point 265, WTRU 215 willperform client MIP procedures, including Client originated MIP BindingUpdate procedures. This client MIP procedure may potentially delayhandover of the WTRU 215 to access point 265 in the second network 210.

Referring to FIG. 3, a wireless communication system 300 includes all ofthe elements identified above with respect to FIG. 2 as well as an MIHserver (MIHS) 305 accessible via the Internet 250. The MIHS 305 controlsvarious aspects of MIH and coordinates services between WTRUs andvarious networks. When WTRU 215 is associated with access point 240, theWTRU 215 may query the MIHS 305 to determine the capabilities ofsurrounding networks. This may be achieved via theMIH_Network_Address_Information_Request message 310, sent from the WTRU215 to the MIHS 305. The prospective point of attachment (PoA) in theprospective network (second network 210) may be identified in themessage 310, in this scenario access point 265. In response, the MIHS305 provides information regarding the characteristics of theprospective network (second network 210), such as whether proxy MIP issupported. The MIHS 305 responds to theMIH_Network_Address_Information_Request message 310 by sending aMIH_Network_Address_Information_Response message 315 including therequested information.

Alternatively, the MIH_Network_Address_Information_Request message 310may simply indicate the MIP preferences of the WTRU 215. In thisscenario, the MIHS 305 will identify networks that are capable ofsupporting the WTRU's 215 MIP preference. Based on the informationreceived from the MIHS 305 in theMIH_Network_Address_Information_Response message 315, the WTRU 215 maychoose access point 240 or access point 265, depending on supported MIPservices and preference.

Referring to FIG. 4, the MIH_Network_Address_Information_Request message400 includes a Source ID field 405, a Destination ID field 410, aCurrent Link ID field 415, a New PoA Identifier field 420, a Target PoAIdentifier List field 425, a Current IP Configuration Method field 430,a Current dynamic host control protocol (DHCP) Server Address field 435,a Current Foreign Agent (FA) Address field 440, a Current Access RouterAddress field 445, and a Requested MIP Mobility Method field 450.

The Source ID field 405 indicates the originator of the message. TheDestination ID field 410 indicates a remote MIH function that will bethe destination of the request. The Current Link ID field 415 indicatesthe source link for handover. The New PoA Identifier field 420 indicatesa new point of attachment identity. The Target PoA Identifier List field425 includes a listing of potential points of attachment that the WTRUis considering for handover. Optionally, the list of potential points ofattachment is sorted by preference, with most preferred points ofattachment listed ahead of least preferred. The Current IP ConfigurationMethod field 430 indicates current IP configuration methods. In oneembodiment, this field is an optional field. The current DHCP ServerAddress field 435 indicates the IP address of a current DHCP Server. Inone embodiment, this field is only included when the WTRU is using adynamic address configuration. In another embodiment, this field isoptional. The Current Foreign Agent (FA) Address field 440 indicates theIP address of a current FA. In one embodiment, this field is onlyincluded when the WTRU is using MIPv4. The Current Access Router Addressfield 445 indicates the IP address of a current access router. In oneembodiment, this field is only included when the WTRU is using IPv6. Inanother embodiment, this field is optional. The Requested MIP MobilityMethod field 450 identifies a WTRU preferred MIP mobility method. TheMIH_Network_Address_Information_Request message 400 may include all ofthe above described fields, or any sub-set of these fields, in anycombination.

In one embodiment, the Requested MIP Mobility Method field 450 includesa Proxy Mobile IPv6 indicator at bit 14. Table 1 below illustrates oneembodiment of the Requested MIP Mobility Method field 450.

TABLE 1 Requested Bit Bits 0-31 Bit 0: IPv4 static MIP Mobility map Bit1: IPv4 dynamic Method Bit 2: Mobile IPv4 with FA (FA- CoA) Bit 3:Mobile IPv4 without FA (Co-located CoA) Bits 4-10: Reserved for IPv4address configuration Bit 11: IPv6 stateless address configuration Bit12: IPv6 stateful address configuration Bit 13: IPv6 manualconfiguration Bit 14: Proxy Mobile IPv6

Referring to FIG. 5, the MIH_Network_Address_Information Responsemessage 500 includes a Source ID field 505, a Destination ID field 510,a Current Link ID field 515, a New PoA Identifier field 520, an IPConfiguration Method field 525, a DHCP Server Address field 530, anAccess Router Address field 535, and a Result Code field 540.

The Source ID field 505 indicates the originator of the message. TheDestination ID field 510 indicates a MIH function that will be thedestination of the message (i.e., the WTRU MIH). The Current Link IDfield 515 indicates the source link for handover. The New PoA Identifierfield 520 indicates the point of attachment of a new access network towhich handover initiation is considered. The IP Configuration Methodfield 525 indicates the IP configuration method of the point ofattachment identified in the PoA Identifier field 510. The DHCP ServerAddress field 530 indicates the DHCP server IP address of the point ofattachment identified in the PoA Identifier field 510. The Access RouterAddress field 535 indicates the IP address of the access routerassociated with the point of attachment identified in the PoA Identifierfield 510. The Result Code field 540 indicates a result code associatedwith the message. The MIH_Network_Address_Information Response message500 may include all of the above described fields, or any sub-set ofthese fields, in any combination.

In one embodiment, the IP Configuration Method field 525 includes aProxy Mobile IPv6 indicator at bit 14. Table 2 below illustrates oneembodiment of the IP Configuration Method field 525.

TABLE 2 IP Bit Bits 0-31 Bit 0: IPv4 static Configuration map Bit 1:IPv4 dynamic Method Bit 2: Mobile IPv4 with FA (FA- CoA) Bit 3: MobileIPv4 without FA (Co-located CoA) Bits 4-10: Reserved for IPv4 addressconfiguration Bit 11: IPv6 stateless address configuration Bit 12: IPv6stateful address configuration Bit 13: IPv6 manual configuration Bit 14:Proxy Mobile IPv6

Proxy MIP is currently defined as Network-based Localized MobilityManagement (NETLMM) support for internet protocol version 6 (IPv6)capable networks. However, the evolution of NETLMM will likely lead tosupport of legacy internet protocol version 4 (IPv4) networks. Inanother embodiment, support of IPv4 proxy MIP may be indicated in themessages described above. This would similarly allow a WTRU to selectthe best handover target during network selection. Additional reservedbits could be used to request and advertise IPv4 functionality.

FIG. 6 is a WTRU 600 and access point 605 configured to transmit andreceive MIH_Network_Address_Information Request andMIH_Network_Address_Information Response messages, as described above.WTRU 600 includes a processor 610, an MIH function 615, and a pluralityof transceivers 620 a . . . 620 n. The processor 610 and MIH function615 are configured to generate and process aMIH_Network_Address_Information Request message as described above. Theplurality of transceivers 620 a . . . 620 n are configured tocommunicate in a plurality of different types of wireless communicationsystems using various radio access technologies, and to transmit aMIH_Network_Address_Information Request message as described above.

Access point 605 includes a processor 625, an MIH function 630, and atransceiver 635. The access point 605 communicates with WTRU 600 via airinterface 640. The processor 625 of the access point 605 processesreceived MIH_Network_Address_Information Request message from WTRU 600via air interface 640 and transceiver 635. The processor 625, incombination with the MIH function 630, of access point 605 forwardsreceived MIH_Network_Address_Information Request message to MIHS 645 andreceives MIH_Network_Address_Information Response messages from the MIHS645. Received MIH_Network_Address_Information_Response messages areforwarded to the WTRU 600 via air interface 640.

Although the features and elements of the present invention aredescribed in the embodiments in particular combinations, each feature orelement can be used alone without the other features and elements of theembodiments or in various combinations with or without other featuresand elements of the present invention. The methods or flow chartsprovided in the present invention may be implemented in a computerprogram, software, or firmware tangibly embodied in a computer-readablestorage medium for execution by a general purpose computer or aprocessor. Examples of computer-readable storage mediums include a readonly memory (ROM), a random access memory (RAM), a register, cachememory, semiconductor memory devices, magnetic media such as internalhard disks and removable disks, magneto-optical media, and optical mediasuch as CD-ROM disks, and digital versatile disks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) module.

1. A method for use in a wireless transmit/receive unit (WTRU), themethod comprising: the WTRU generating a query message that includes anidentifier of a preferred Internet Protocol (IP)-based mobility protocolof the WTRU; the WTRU transmitting the query message to a server viawireless network; and the WTRU receiving a response message from theserver via the wireless network, wherein the response message isresponsive to the query message, and wherein the response messageincludes an identifier of a target point of attachment and an identifierof an IP-based mobility protocol supported by the target point ofattachment.
 2. The method of claim 1, further comprising: the WTRUdetermining to perform a handoff to the target point of attachment basedon the IP-based mobility protocol supported by the target point ofattachment; and the WTRU performing the handoff to the target point ofattachment
 3. The method of claim 1, wherein the query message furtherincludes the identifier of the target point of attachment.
 4. The methodof claim 1, wherein the preferred IP-based mobility protocol of the WTRUis a Client Mobile IP (CMIP) protocol.
 5. The method of claim 4, whereinthe CMIP protocol is a Mobile IPv4 with Foreign Agent (FA) protocol or aMobile IPv4 without FA protocol.
 6. The method of claim 1, wherein thepreferred IP-based mobility protocol of the WTRU is a Proxy Mobile IP(PMIP) protocol.
 7. The method of claim 1, wherein the PMIP protocol isa PMIPv4 or a PMIPv6 protocol.
 8. The method of claim 1, wherein theserver is a Media Independent Handover (MIH) server, and wherein thequery message and the response message are MIH messages.
 9. A wirelesstransmit/receive unit (WTRU), the WTRU comprising: a processorconfigured to generate a query message that includes an identifier of apreferred Internet Protocol (IP)-based mobility protocol of the WTRU; atransceiver configured to: transmit the query message to a server viawireless network; and receive a response message from the server via thewireless network, wherein the response message is responsive to thequery message, and wherein the response message includes an identifierof a target point of attachment and an identifier of an IP-basedmobility protocol supported by the target point of attachment.
 10. TheWTRU of claim 9, wherein: the processor is further configured todetermine to perform a handoff to the target point of attachment basedon the IP-based mobility protocol supported by the target point ofattachment; wherein the transceiver is further configured to perform thehandoff to the target point of attachment
 11. The WTRU of claim 9,wherein the query message further includes the identifier of the targetpoint of attachment.
 12. The WTRU of claim 9, wherein the preferredIP-based mobility protocol of the WTRU is a Client Mobile IP (CMIP)protocol or a Proxy Mobile IP (PMIP) protocol.
 13. The WTRU of claim 9,wherein the server is a Media Independent Handover (MIH) server, andwherein the query message and the response message are MIH messages. 14.A method for use in a server, the method comprising: the serverreceiving a query message from a wireless transmit/receive unit (WTRU)via a wireless network, wherein the query message includes an identifierof a preferred Internet Protocol (IP)-based mobility protocol of theWTRU; the server, responsive to the query message, transmitting aresponse message to the WTRU via the wireless network, wherein theresponse message includes an identifier of a target point of attachmentand an identifier of an IP-based mobility protocol supported by thetarget point of attachment.
 15. A server, comprising: a receiverconfigured to receive a query message from a wireless transmit/receiveunit (WTRU) via a wireless network, wherein the query message includesan identifier of a preferred Internet Protocol (IP)-based mobilityprotocol of the WTRU; a processor configured to generate a responsemessage, wherein the response message is responsive to the querymessage, and wherein the response message includes an identifier of atarget point of attachment and an identifier of an IP-based mobilityprotocol supported by the target point of attachment; and a transmitterconfigured to transmit the response message to the WTRU via the wirelessnetwork.